How to Install a Low Voltage Doorbell

Install a doorbell when you can't hear the knocker.

Install a doorbell in your home so you never miss a visitor. A low-voltage doorbell requires a transformer to step the 120-volt household electricity down to 10-, 12-, or 24-volts depending on the doorbell you install. Installing the low-voltage transformer requires tapping into an existing electrical circuit, installing a new electrical box and running wire from the doorbell button back to the doorbell. Some basic electrical wiring knowledge is helpful but not necessary.

1

Find a location to install the door chime, either next to your front door or in your hallway. Locate the chime on the wall directly above a receptacle to have easier access to the power supply.

2

Trace around a plastic 34 cubic inch double-gang old-work box onto the wall at your chime location. Cut around the trace line with a handheld rotary tool fitted with a drywall cutting accessory and cutting guide attachment to create an opening in the wall.

3

Tap into the existing receptacle in the hallway to power the low-voltage transformer behind the door chime. Plug a lamp or radio into the receptacle. Turn off 20-amp breakers in your panel box until the lamp or radio turns off.

4

Remove the screw holding the cover on the receptacle. Remove the two screws holding the receptacle in the outlet box on the wall. Loosen the screws holding the black, white and copper wires to the side of the receptacle. Remove the wires from underneath the screws on the receptacle, and set the receptacle aside.

5

Feed a fish tape through the top of the outlet box and up to the opening you created in the wall. Bend a length of 12/2 nonmetallic electrical cable around the hook in the fish tape. Use electrical tape to hold the cable to the fish tape.

6

Reel the fish tape down through the wall to pull the new length of cable to supply power to the transformer. Release the electrical cable from the fish tape.

7

Rip the exterior cable sheath from each end of the new electrical cable to expose the interior wires with a cable ripper. Remove at least 1/2 inch of electrical wire insulation from each interior wire with a pair of wire cutter/strippers.

8

Cut a 6-inch piece of 12-gauge black solid wire, 12-gauge white solid wire and 12-gauge green solid wire. Remove at least 1/2 inch of the insulation surrounding each end of the 6-inch pieces of wire.

9

Connect the 6-inch black wire with the two black wires inside the outlet box by twisting a wire connector onto all three wires. Repeat the same connections for the two white wires inside the outlet box, connecting them with the 6-inch white wire, and the two bare copper wires must connect with the 6-inch green wire.

10

Bend the loose ends of the three 6-inch wires into hooks with needle nose pliers. Hook the black wire around the copper terminal screw on the receptacle, the white wire around the silver terminal of the receptacle and the green wire around the green terminal on the receptacle. Use either a Phillips or slotted screwdriver to tighten the terminal screws.

11

Reinstall the receptacle in the outlet box and replace the receptacle cover.

12

Create a small hole in the exterior wall next to your door where you want to install the push button. Access the attic above the doorbell button. Drill a hole into the top plate of the exterior wall with a 1/2-inch drill bit.

13

Feed the fish tape though the hole in the top plate and down to the opening for the push button. Secure 20/2 twisted bell wire to the fish tape with electrical tape. Use the fish tape to pull the wire in the attic. Release the 20/2 twisted bell wire from the fish tape.

14

Pull the wire across the attic and over to the wall above the opening you created. Drill a hole into the top plate above the opening in the wall.

15

Feed the fish tape up through the wall and through the hole you drilled in the top plate. Secure the bell wire to the fish tape and pull it from the attic and out the opening in the wall.

16

Insert the electrical cable and bell wire through an opening in the back of the plastic 34 cubic inch double-gang, old work box. Push the plastic box into the hole you created in the wall board. Turn the two screws located on the face of the box until tight. This action secures the plastic 34-cubic inch double-gang, old work box to the wall.

17

Strip 1/2-inch of insulation off both ends of the 20/2 twisted bell wire with the wire stripper. Wrap the red wire around one terminal on the back of the push button and wrap the white wire around the remaining terminal on the button. Attach the button to the wall with the screws provided with the doorbell button.

18

Connect the black wire from the 12/2 electrical cable to the black wire from the low-voltage doorbell transformer by twisting a wire connector onto the two wires. Connect the 12/2 white wire to the white wire from transformer with another wire connector, and connect the green wire from the transformer to the bare copper wire. Set the transformer into the plastic old work box with the terminal screws on the transformer facing out.

19

Wrap the white wire from the 20/2 twisted bell wire around the terminal screws on the transformer labeled as “In.” Tighten the screw to hold the wire to the transformer.

20

Cut an 8-inch length of the 20/2 twisted bell wire. Pull the white wire away from the red wire. Strip both ends of the 20-gauge white wire.

21

Wrap one end of the 8-inch length of 20-gauge white wire around the terminal screw labeled as “Out.” Tighten the screw to hold the wire to the door bell transformer.

22

Pull the red and white bells wires through an opening in the doorbell base. Attach the base to the plastic box in the wall using the screws provided with the doorbell.

23

Wrap the red wire around the terminal screw on the doorbell labeled as “Front,” and the white wire around the terminal screw labeled as “Transformer.” Snap the doorbell cover over the doorbell and turn the 20-amp breaker back on inside your panel box.

About the Author

Cecilia Harsch has been writing professionally since 2009. She writes mainly home improvement, health and travel articles for various online publications. She has several years of experience in the home-improvement industry, focusing on gardening, and a background in group exercise instruction. Harsch received her Certified Nurses Assistant license in 2004. She attended Tarrant County College and studied English composition.